The Clinical Core will support Projects 1-5 by providing nursing and other personnel to support in the most cost-effective manner the recruitment and screening of normal subjects, the phenotyping of patients with specific autonomic disorders by the performance of individual studies and the maintenance of the Autonomic Dysfunction Center Database. Shared study rooms and equipment maximize the availability of resources and provide consistency in the performance of studies and in data analysis. The involvement of Core personnel in these studies will enhance the ability of each Project to benefit from the data obtained in the other Projects. The Core will support state-of-the-art functional assessment of sympathetic nerve activity in man (norepinephrine spillover, microneurography, spectral analysis of physiological signals), cardiac output determination, multiple methods for the measurement of absolute plasma volume and fluid shifts, and support for specialized analytic methods for the characterization of baroreflex function (including neck suction baroreflex testing). The Core will also provide tritiated norepinephrine (more cost-effectively utilized when purchased in bulk) and microneurography supplies.